Ladder

ABSTRACT

A ladder having a side rail with a noncircular opening therethrough. A first element extends through the opening and has a portion complementing the configuration of the opening. The first element also has a portion forming a flange and another portion secured to an adjacent rung. A second element is secured to the first element and has a flange which cooperates with the flange of the first element to sandwich the side rail therebetween.

LADDER BACKGROUND OF THE. INVENTION This invention relates generally to ladders and, more specifically, to an improved means to secure a rung to the side rail of the ladder. The term ladder as used herein includes scaffold frames, and other devices, wherein rung-to-rail connections may be employed. 7

It is, of course, necessary in the construction of a ladder to provide a sound and secure connection between the side rail and the rung so as to achieve a rigid structure. Another requirement is that the rung should be secured against rotation, about its own axis, relative to the side rail since such rota,- tion makes use of the ladder very difficult and, in fact, unsafe. Means for achieving such connections have been proposed in the past and have been suitable for one application or another. Many, however, present significant drawbacks'with respect to cost, ease of manufacture, and long life. It is an object of this invention to provide an improved rung-to-rail connection which achieves a secure and, rigid construction and: which is relatively inexpensive and easy to manufacture.

SUMMARY or THE INVENTION Briefly stated, in accordance with one. aspect of the present invention, a ladder is provided having at least, one side rail with a noncircular opening therethrough. Means are provided to connect a rung to the side rail and include a first element having a first portion defining a first flange, a-second portion extending through the opening, and a third portion engaging the rung. The second portion has an external configuration complementing the configuration of the'ope'ning. A second element is secured to the first element and defines a. second flange. The first flange and the second flange are disposed on opposite sides of the side rail. to. sandwich the side rail therebetween to secure the first and second elements to the side rail, Means are provided to secure the third portion to the rung whereby the rung is secured to the side rail.

BRIEF DESCRIPTION OF THE DRAWING While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention, it is believed the invention will be better understood from the following description of the preferred embodiments taken in connection with the accompanying drawing, in which:

FIG. I is an exploded view of one embodiment of the present invention;

FIG. 2 is a fragmentary sectional view of the embodiment of FIG. 1;

FIG. 3 is a fragmentary sectional view of another embodiment of the present invention;

FIG. 4 is a fragmentary sectional view of another embodiment of the present invention;

FIG. 5 is a fragmentary sectional view of another embodiment of the present invention; and, p

FIG. 6 is a fragmentary sectional view of another embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to, the drawing, and initially to FIG. 1

thereof, there is illustrated a side rail 10 of a ladder to which a.

rung 11 is to be connected in a secure fashion. Side rail 10 has two flange elements 12 interconnected by a, central web 13,, it being understood that this type of side rail is shown for illustrative purposes only and that side rail 10, could, for example, assume a C-shaped configuration or any other conventional ladder side rail configuration. Web 13 of side rail 10 has a noncircular opening 14 therethrough.

A first element 15 has a first portion defining a flange 16, a second portion 17 which extends through. opening 14 and a third portion, 18 to engage rung ll. Portion 17. of element 15 has an external configuration which complements the internal configuration of opening 14. As used herein, the term "complement means that the external configuration of portion 17 is such that it snuggly fits within opening 14 and is, of course, of the same general configuration. In other words, if opening 14. is square, the external configuration of portion 17 is square, as illustrated in FIG. 1. Itis to be understood, however, that opening 14 and portion 17 can assume substantially any noncircular configuration such as, for example, triangular, pentagonal, hexagonal, or the like. As will become evident as this description proceeds, the noncircular requirement is to provide a structure wherein element 15. is secured against rotation about its own axis relative to side rail 10.

A second element 19 is provided and comprises a flange 20 at one end of a shaft portion 21. The other end of shaft portion 21 has a plurality of fingers 22 defined by slots 23. Fingers 22 extend through tubular portion 18 of element 15 and have, at their terminal ends, tabs, 24 which engage the end of portion 18. to secure elements 15 and 19 together.

It should be evident now that when elements Hand 19 are secured together as described above, a unitary structure is provided which is securely connected to web E3 of side rail 10. This connection is achieved by the fact that flanges l6 and 20 sandwich web 13 therebetween. It shouldbe noted that portion 17 of element 15 has a thickness no greater than the thickness of web. 13 and may in order to compensate for tolerances, have a thickness somewhat less. than the thickness of web 13 to assure that flanges 16 and 20: come into contact with web 13.

In the preferred form of the present invention, rung I1 is tubular and portion 18' of element l5 iscylindrical and extends into rung 11. With this arrangement, rung I1 is secured to element 15 by means of an adhesive applied between portion l8 and the inner surface of rung 11. Any suitable bonding agent may serve as the adhesive. For example, a cement or glue suitable for bonding the materials, of rung 11 and element 15 may be employed. As presently envisioned, the preferred form of the present invention would have rung 11 formed from alu minum. and element 15 formed from some suitable plastic material.

Thus, it should now be apparent that when rung 11 is secured to portion 18 of element 15 by some suitable bonding agent, rung 11 is rigidly and securely connected to side rail 10 due to the sandwiching effect of flanges 16 and 20. Moreover, the connection is secured against rotation relative to side rail 10. due to the complementing noncircular configurations of portion 17' and opening 14.

Referring now to FIG. 3, there is illustrated an embodiment of the present invention which comprises aslight modification of the embodiment of FIGS. 1 and 2. Similar elements have been given the same reference numerals, for purposes of simplification. In this embodiment, fingers 22 are provided with inclined surfaces 25 which cooperate with a chamfer or taper 26 on the inner surface of portion 18 adjacent its terminal end.

Thus, inclined surface 25 serves the same function as tab 24 in the embodiment described above. The advantage of the embodiment of FIG. 3 is that the relationship between surface 25 and chamfer 26 allows some axial displacement between portion 18 and fingers 22. This axial displacement can, be related back to a variance in spacing between flanges 16 and 20. Thus, the relationship between inclined surface 25 and chamfer 26 allows for any variance in the thickness of web 13, and a resulting variance the spacing of flanges 16 and 20, while still providing a rigid and. secure connection between, the elements 15 and 19 and side rail 10. All, other aspects of the. embodiment of FIG. 3 are identical to the embodiment of FIG. 2.

Referring now to FIG. 4, another embodiment of the present invention is illustrated. The embodiment of FIG. 4 is similar to the embodiment of FIGS. 1 and 2 with the exception.

thereon. With this arrangement, element 19 is threaded into engagement with element until flanges 16 and securely abut the opposite surfaces of web 13 to sandwich web 13 therebetween. Of course, portion 17 fits into a noncircular opening in a manner identical to that described above in connection with the embodiment of FIGS. 1 and 2. Once threaded engagement has been achieved between elements 15 and 19, rung 11 may be secured to portion 18 by means of a suitable adhesive. I

Referring now to FIG. 5, another embodiment of the present invention is illustrated. In this embodiment, a first element 31 is provided with a first portion defining a flange 32, a second portion 33 and a third portion 34. Second portion 33 fits within a noncircular opening 35 in web 13 and has an external configuration which complements the configuration of opening 35. A second element 36 has a flange 37 and internal screw thread 38 which cooperates with an external screw thread 39 on first element 31. With this arrangement, element 36 is slipped over portion 34 until it encounters screw thread 39 at which time it is threaded onto element 31 until flange 37 engages web 13 so that flanges 37 and 32 sandwich web 13 therebetween in a secure and rigid fashion. Following this, rung 11 is slipped over portion 34 and a suitable adhesive is employed to secure rung 11 to portion 34 in a manner similar to that described above in connection with the embodiment of FIGS. 1 and 2.

Referring now to FIG. 6, there is illustrated another embodiment of the present invention comprising a first element 40 having a first portion defining a flange 41, a second portion 42 which is received in, and has an outer configuration complementing, a noncircular opening 43 in web 13, and a third portion 44. The embodiment of FIG. 6 also includes a second element comprising a flange 45. With this arrangement, element 40 is slipped through opening 43 until portion 44 becomes aligned therewith. Flange 45 is then slipped over portion 44 of element 40 until it engages web 13 of side rail 10. At this point, the two elements are clamped into secure engagement with web 13 by means of a suitable clamping tool (not shown) and an adhesive is applied to bond flange 45 and element 40 together. Rung 11 is secured to portion 44 by means of a suitable bonding agent or adhesive as described above in connection with the embodiments of FIGS. 1 and 2. If desired, the application of adhesive and the bonding operation of flange 45 to element 40 may be carried out concurrently with the bonding of rung 1 l to portion 44.

It should be understood that although in the preferred form of the present invention elements 15 and 19 are formed from a suitable plastic material and rung l1 and side rail 10 are formed from aluminum extrusions, other suitable materials may be employed without departing from the spirit of the present invention. Also, the precise bonding agents or adhesives used in practicing this invention are not critical to the invention as long as they are suitable to bond together the two materials being bonded.

It should now be evident that the present invention provides and rigid construction and which is relatively inexpensive and easy to manufacture.

As will be evident from the foregoing description, certain aspects of the invention are not limited to the particular details of construction of the examples illustrated, and is is contemplated that various other modifications or applications will occur to those skilled in the art. It is therefore intended that the appended claims shall cover such modifications and applications as do not depart from the true spirit and scope of the invention.

1 claim:

1. A ladder comprising:

at least one side rail having a noncircular opening therethrough; 1

at least one rung;

a first element having a first portion defining a first flange, a second portion extending through said opening and a third portion engagingsaid rung;

said second portion avmg an external configuration complementing the configuration of said opening;

a second element secured to said first element and defining a second flange;

said first flange and said second flange being disposed on opposite sides of said side rail to sandwich said side rail therebetween to secure said first and second elements to said side rail; and

means to secure said third portion to said rung whereby said rung is secured to said side rail.

2. The invention of claim 1 wherein said rung is tubular and said third portion extends into said rung.

3. The invention of claim 2 wherein said means to secure said third portion to said rung comprises an adhesive between the outer surface of said third portion and the inner surface of said tubular rung.

4. The invention of claim 1 wherein said third portion in tubular and said second element has at least one finger extending through said third portion and terminating beyond the end of said third portion, said finger having a tab at its terminal end engaging the end of said third portion to thereby secure said first and second elements together.

5. The invention of claim 4 wherein said third portion adjacent its terminal end has a chamfer and said tab has an inclined surface to cooperate with said chamfer to secure said first and second elements together.

6. The invention of claim 1 wherein said first element has an external screw thread adjacent said second portion, said second element has an internal screw thread, and said first and second elements are secured together by the threaded engagement of said screw threads.

' 7. The invention of claim 1 wherein said second element has a central opening through which said third portion extends and said first and second'elements are secured together by an adhesive between said second element and said third portion.

8. The invention of claim 1 wherein said first element has a central bore with an internal screw thread therein, said second element has a shaft portion with an external screw thread thereon, and said first and second elements are secured together by the threaded engagement of said screw threads. 

1. A ladder comprising: at least one side rail having a noncircular opening therethrough; at least one rung; a first element having a first portion defining a first flange, a second portion extending through said opening and a third portion engaging said rung; said second portion having an external configuration complementing the configuration of said opening; a second element secured to said first element and defining a second flange; said first flange and said second flange being disposed on opposite sides of said side rail to sandwich said side rail therebetween to secure said first and second elements to said side rail; and means to secure said third portion to said rung whereby said rung is secured to said side rail.
 2. The invention of claim 1 wherein said rung is tubular and said third portion extends into said rung.
 3. The invention of claim 2 wherein said means to secure said third portion to said rung comprises an adhesive between the outer surface of said third portion and the inner surface of said tubular rung.
 4. The invention of claim 1 wherein said third portion in tubular and said second element has at least one finger extending through said third portion and terminating beyond the end of said third portion, said finger having a tab at its terminal end engaging the end of said third portion to thereby secure said first and second elements together.
 5. The invention of claim 4 wherein said third portion adjacent its terminal end has a chamfer and said tab has an inclined surface to cooperate with said chamfer to secure said first and second elements together.
 6. The invention of claim 1 wherein said first element has an external screw thread adjacent said second portion, said second element has an internal screw thread, and said first and second elements are secured together by the threaded engagement of said screw threads.
 7. The invention of claim 1 wherein said second element has a central opening through which said third portion extends and said first and second elements are secured together by an adhesive between said second element and said third portion.
 8. The invention of claim 1 wherein said first element has a central bore with an internal screw thread therein, said second element has a shaft portion with an external screw thread thereon, and said first and second elements are secured together by the threaded engagement of said screw threads. 